Initial vendor packages

Signed-off-by: Valentin Popov <valentin@popov.link>

vendor/once_cell/examples/bench.rs

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+use std::mem::size_of;
+
+use once_cell::sync::OnceCell;
+
+const N_THREADS: usize = 32;
+const N_ROUNDS: usize = 100_000_000;
+
+static CELL: OnceCell<usize> = OnceCell::new();
+
+fn main() {
+    let start = std::time::Instant::now();
+    let threads =
+        (0..N_THREADS).map(|i| std::thread::spawn(move || thread_main(i))).collect::<Vec<_>>();
+    for thread in threads {
+        thread.join().unwrap();
+    }
+    println!("{:?}", start.elapsed());
+    println!("size_of::<OnceCell<()>>()   = {:?}", size_of::<OnceCell<()>>());
+    println!("size_of::<OnceCell<bool>>() = {:?}", size_of::<OnceCell<bool>>());
+    println!("size_of::<OnceCell<u32>>()  = {:?}", size_of::<OnceCell<u32>>());
+}
+
+fn thread_main(i: usize) {
+    for _ in 0..N_ROUNDS {
+        let &value = CELL.get_or_init(|| i);
+        assert!(value < N_THREADS)
+    }
+}

vendor/once_cell/examples/bench_acquire.rs

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+//! Benchmark the overhead that the synchronization of `OnceCell::get` causes.
+//! We do some other operations that write to memory to get an imprecise but somewhat realistic
+//! measurement.
+
+use once_cell::sync::OnceCell;
+use std::sync::atomic::{AtomicUsize, Ordering};
+
+const N_THREADS: usize = 16;
+const N_ROUNDS: usize = 1_000_000;
+
+static CELL: OnceCell<usize> = OnceCell::new();
+static OTHER: AtomicUsize = AtomicUsize::new(0);
+
+fn main() {
+    let start = std::time::Instant::now();
+    let threads =
+        (0..N_THREADS).map(|i| std::thread::spawn(move || thread_main(i))).collect::<Vec<_>>();
+    for thread in threads {
+        thread.join().unwrap();
+    }
+    println!("{:?}", start.elapsed());
+    println!("{:?}", OTHER.load(Ordering::Relaxed));
+}
+
+#[inline(never)]
+fn thread_main(i: usize) {
+    // The operations we do here don't really matter, as long as we do multiple writes, and
+    // everything is messy enough to prevent the compiler from optimizing the loop away.
+    let mut data = [i; 128];
+    let mut accum = 0usize;
+    for _ in 0..N_ROUNDS {
+        let _value = CELL.get_or_init(|| i + 1);
+        let k = OTHER.fetch_add(data[accum & 0x7F] as usize, Ordering::Relaxed);
+        for j in data.iter_mut() {
+            *j = (*j).wrapping_add(accum);
+            accum = accum.wrapping_add(k);
+        }
+    }
+}

vendor/once_cell/examples/lazy_static.rs

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+extern crate once_cell;
+
+use once_cell::sync::{Lazy, OnceCell};
+use std::collections::HashMap;
+
+static HASHMAP: Lazy<HashMap<u32, &'static str>> = Lazy::new(|| {
+    let mut m = HashMap::new();
+    m.insert(0, "foo");
+    m.insert(1, "bar");
+    m.insert(2, "baz");
+    m
+});
+
+// Same, but completely without macros
+fn hashmap() -> &'static HashMap<u32, &'static str> {
+    static INSTANCE: OnceCell<HashMap<u32, &'static str>> = OnceCell::new();
+    INSTANCE.get_or_init(|| {
+        let mut m = HashMap::new();
+        m.insert(0, "foo");
+        m.insert(1, "bar");
+        m.insert(2, "baz");
+        m
+    })
+}
+
+fn main() {
+    // First access to `HASHMAP` initializes it
+    println!("The entry for `0` is \"{}\".", HASHMAP.get(&0).unwrap());
+
+    // Any further access to `HASHMAP` just returns the computed value
+    println!("The entry for `1` is \"{}\".", HASHMAP.get(&1).unwrap());
+
+    // The same works for function-style:
+    assert_eq!(hashmap().get(&0), Some(&"foo"));
+    assert_eq!(hashmap().get(&1), Some(&"bar"));
+}

vendor/once_cell/examples/reentrant_init_deadlocks.rs

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+fn main() {
+    let cell = once_cell::sync::OnceCell::<u32>::new();
+    cell.get_or_init(|| {
+        cell.get_or_init(|| 1);
+        2
+    });
+}
+
+/// Dummy test to make it seem hang when compiled as `--test`
+/// See https://github.com/matklad/once_cell/issues/79
+#[test]
+fn dummy_test() {
+    std::thread::sleep(std::time::Duration::from_secs(4));
+}

vendor/once_cell/examples/regex.rs

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+use std::{str::FromStr, time::Instant};
+
+use regex::Regex;
+
+macro_rules! regex {
+    ($re:literal $(,)?) => {{
+        static RE: once_cell::sync::OnceCell<regex::Regex> = once_cell::sync::OnceCell::new();
+        RE.get_or_init(|| regex::Regex::new($re).unwrap())
+    }};
+}
+
+fn slow() {
+    let s = r##"13.28.24.13 - - [10/Mar/2016:19:29:25 +0100] "GET /etc/lib/pChart2/examples/index.php?Action=View&Script=../../../../cnf/db.php HTTP/1.1" 404 151 "-" "HTTP_Request2/2.2.1 (http://pear.php.net/package/http_request2) PHP/5.3.16""##;
+
+    let mut total = 0;
+    for _ in 0..1000 {
+        let re = Regex::new(
+            r##"^(\S+) (\S+) (\S+) \[([^]]+)\] "([^"]*)" (\d+) (\d+) "([^"]*)" "([^"]*)"$"##,
+        )
+        .unwrap();
+        let size = usize::from_str(re.captures(s).unwrap().get(7).unwrap().as_str()).unwrap();
+        total += size;
+    }
+    println!("{}", total);
+}
+
+fn fast() {
+    let s = r##"13.28.24.13 - - [10/Mar/2016:19:29:25 +0100] "GET /etc/lib/pChart2/examples/index.php?Action=View&Script=../../../../cnf/db.php HTTP/1.1" 404 151 "-" "HTTP_Request2/2.2.1 (http://pear.php.net/package/http_request2) PHP/5.3.16""##;
+
+    let mut total = 0;
+    for _ in 0..1000 {
+        let re: &Regex = regex!(
+            r##"^(\S+) (\S+) (\S+) \[([^]]+)\] "([^"]*)" (\d+) (\d+) "([^"]*)" "([^"]*)"$"##,
+        );
+        let size = usize::from_str(re.captures(s).unwrap().get(7).unwrap().as_str()).unwrap();
+        total += size;
+    }
+    println!("{}", total);
+}
+
+fn main() {
+    let t = Instant::now();
+    slow();
+    println!("slow: {:?}", t.elapsed());
+
+    let t = Instant::now();
+    fast();
+    println!("fast: {:?}", t.elapsed());
+}

vendor/once_cell/examples/test_synchronization.rs

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+//! Test if the OnceCell properly synchronizes.
+//! Needs to be run in release mode.
+//!
+//! We create a `Vec` with `N_ROUNDS` of `OnceCell`s. All threads will walk the `Vec`, and race to
+//! be the first one to initialize a cell.
+//! Every thread adds the results of the cells it sees to an accumulator, which is compared at the
+//! end.
+//! All threads should end up with the same result.
+
+use once_cell::sync::OnceCell;
+
+const N_THREADS: usize = 32;
+const N_ROUNDS: usize = 1_000_000;
+
+static CELLS: OnceCell<Vec<OnceCell<usize>>> = OnceCell::new();
+static RESULT: OnceCell<usize> = OnceCell::new();
+
+fn main() {
+    let start = std::time::Instant::now();
+    CELLS.get_or_init(|| vec![OnceCell::new(); N_ROUNDS]);
+    let threads =
+        (0..N_THREADS).map(|i| std::thread::spawn(move || thread_main(i))).collect::<Vec<_>>();
+    for thread in threads {
+        thread.join().unwrap();
+    }
+    println!("{:?}", start.elapsed());
+    println!("No races detected");
+}
+
+fn thread_main(i: usize) {
+    let cells = CELLS.get().unwrap();
+    let mut accum = 0;
+    for cell in cells.iter() {
+        let &value = cell.get_or_init(|| i);
+        accum += value;
+    }
+    assert_eq!(RESULT.get_or_init(|| accum), &accum);
+}